Pulse doppler and navigation system

Claim 2

In combination in a pulsed Doppler navigation system, transducer means for radiating emitted energy downward and outward along a desired sensing axis and for recovering a reflected portion of said emitted pulsed energy, said returned energy portion having a frequency dependent upon the speed of said transducer means along said sensing axis; gated, normally open, feedback loop means for generating a continuous periodic output signal of a frequency related to that of the recovered pulsed energy; and means for gating said feedback loop closed when a recovered signal is available for processing.

Claim 3

In combination in a pulsed Doppler navigation system, transducer means for radiating emitted energy downward and outward along a desired sensing axis and for recovering a reflected portion of said emitted pulsed energy, said returned energy portion having a frequency dependent upon the speed of said transducer means along said sensing axis; gated, normally open, feedback loop means for generating a continuous periodic output signal of a frequency related to that of the recovered pulsed energy; and means for gating said feedback loop closed when a recovered signal is available for processing.

Claim 4

In combination in a pulsed Doppler navigation system, transducer means for radiating emitted energy downward and outward along a desired sensing axis and for recovering a reflected portion of said emitted pulsed energy, said returned energy portion having a frequency dependent upon the speed of said transducer means along said sensing axis; gated, normally open, feedback loop means for generating a continuous periodic output signal of a frequency related to that of the recovered pulsed energy; and means for gating said feedback loop closed when a recovered signal is available for processing.

Claim 5

A combination as in claim 1 further comprising a source of oscillations to be emitted by said transducer means, and circuit means responsive to the difference in frequency between the output of said oscillation source and the continuous periodic output signal of said feedback means for computing the velocity of said transducer means along said sensing axis.

Claim 6

A combination as in claim 2 wherein said feedback loop means comprises a voltage controlled oscillator, error signal means responsive to the output of said voltage controlled oscillator and to said returned pulse energy for producing a potential for controlling said oscillator, first gating means for selectively connecting said error signal means and said voltage controlled oscillator, control voltage storage means, and second gating means selectively connecting said control voltage storing means to said voltage controlled oscillator.

Claim 7

A combination as in claim 3 wherein said control voltage storing means comprises a sample and hold circuit, and wherein said gated feedback loop means further comprises third gating means selectively connecting said error sensing means and said sample and hold means.

Claim 8

A combination as in claim 4 wherein said error sensing means comprises a flip-flop having two input terminals thereon respectively supplied with said returned pulsed signals and the output of said voltage controlled oscillator, and average value detector means connected to the output of said flip-flop.

Claim 9

A combination as in claim 5 further comprising slow response coupling means connected intermediate said third gating means and said sample and hold means.

Claim 10

A combination as in claim 6 wherein said flip-flop included in said error sensing means comprises a J-K flip-flop having set and clock input terminals, said returned signals being connected to said set flip-flop input terminal and the output of said voltage controlled oscillator being connected to said clock input terminal.

Claim 11

A combination as in claim 2 further comprising means for disabling said feedback loop means when the vertical orientation of said system departs substantially from vertical.

Claim 12

A combination as in claim 8 wherein said vertical departurE disabling means includes gate means for inhibiting said feedback loop means, inclinometer means for providing an output signal which characterizes the relative vertical orientation of said system, and circuit means for disabling said gating means when the output of said inclinometer means departs from a vertical signaling condition.

Claim 13

A combination as in claim 2 further comprising means for rotating said sensing axis with respect to a vessel in which said combination is mounted.

Claim 14

A combination as in claim 2 further comprising means for obtaining Doppler frequency shift velocity information along two orthogonal axes, and wherein said transducer means includes two transducer elements displaced at right angles on a single transducer pod.

Claim 15

A combination as in claim 2 wherein said feedback loop gating means comprises means for gating said feedback loop means into an operative condition about the midpoint of said returned energy pulses recovered by said transducer means.

Claim 16

A combination as in claim 12 wherein said feedback loop gating means comprises a relatively fast ramp generator, a relatively slow ramp generator, means for enabling the output of said slow ramp generator following transmission of a pulse of emitted energy, additional gating means for enabling said fast ramp generator at the beginning of a recovered energy pulse, and comparator means for generating a strobe gating pulse for rendering said feedback loop mean operative when the output of said fast ramp generator attains a predetermined relationship with the output of said slow ramp generator.

Claim 17

A combination as in claim 13 further comprising timing means constraining said navigation system to sequentially radiate energy pulse bursts including transmit gate means intermediate said source of oscillations and said transducer means, and means responsive to each output of said comparator means for enabling said transmit gate means.

Claim 18

A combination as in claim 14 further comprising a relaxation oscillator, threshold means for selectively enabling said transmit gate means, and means for selectively resetting said relaxation oscillator responsive to a pulse generated by said comparator means.

Claim 19

A combination as in claim 2 wherein said computing circuit means comprises means for generating first and second digital square wave signals each having a frequency reflecting the difference in frequency between the emitted and returned signals and having a relative phase dependent upon the direction of motion of said transducer means along said axis, means for sampling said second square wave signal during a predetermined point in the cycle of said first square wave signal, means responsive to the output of said sampling means for presenting information identifying the relative direction of said transducers along said sensing axis, means for developing a sequential pulse train dependent in frequency upon the frequency of one of said square waves, digital counter means for counting the pulses produced by said pulse developing means, information outputting means, latching memory means for operating said information outputting means in accordance with the contents of said counter during a sampling interval, and time gate means for periodically initializing said counter to a reference state and for periodically supplying control signals to said latching memory means.

Claim 20

A combination as in claim 16 wherein said time gate means includes means for varying said counter initializing periodicity and said control signal supplying periodicity responsive to variations in the acoustical propagating characteristic of the emitted energy propagating medium.

Claim 21

A combination as in claim 17 wherein said time gate means includes a reference oscillator, means for supplying a signal having a frequency dependent upon the acoustical propagating characteristic of the wave propagating medium, mixer and filter means for obtaining an output signal dependent upon the difference in frequency between the output Of said reference oscillator and the output of said propagation characteristic dependent signal supplying means, and scaler means for periodically supplying pulses responsive to a plurality of input oscillation cycles supplied thereto by the output of said mixer and filter means.

Claim 22

A combination as in claim 18 wherein said time gate means further includes a flip-flop connected to said scaler means, said scaler means being adapted to selectively set said flip-flop, and delay means connected to an output of said flip-flop for resetting said flip-flop.

Claim 23

A combination as in claim 16 wherein said first and second digital square wave generating means comprise first and second mixer and filter means, squaring circuit means connected to the output of each of said input filters, means for supplying said emitted and returned signals to said first and second mixer and filter means, and means connected at the input of said second mixer and filter for producing a 90* relative phase shift between said emitted and said returned signals.

Claim 24

A combination as in claim 16 further comprising scaler means connected intermediate said digital counter means and said pulse developing means.

Claim 25

A combination as in claim 21 further comprising switching means for varying the pulse frequency division factor for said scaler means.

Claim 26

A combination as in claim 22 wherein said second square wave sampling means includes means for generating an output pulse responsive to a voltage transient condition for said first square wave signal, first and second AND gates each having two inputs, said voltage transient responsive pulse being supplied to one input of each of said AND gates, means for supplying said second square wave in inverted relationships to a second input of said first and second AND gates, an output from one of said AND gates signaling motion in one direction along said sensing axis and an output from the other of said AND gates signaling motion in the other direction along said sensing axis.

Claim 27

A combination as in claim 23 wherein said sampling means further comprises third and fourth AND gates, means for supplying one of said square wave signals to each of said third and fourth AND gates, a flip-flop selectively set by said first AND gate and selectively reset by said second AND gate, one output from said flip-flop being connected to said third AND gate and the other output of said flip-flop being connected to said fourth AND gate.

Claim 28

A combination as in claim 24 wherein said relative direction identifying means comprises verifier means for signaling the relative direction only after the incidence of a plurality of pulses corresponding to motion in a like direction.

Claim 29

A combination as in claim 25 wherein said verifier means includes first and second additional counting means respectively connected to said third and fourth AND gates, first and second verifier flip-flops selectively set by said first and second additional counters, additional latched memory means for developing a relative direction display dependent upon the relative states of said verifier flip-flops, and means for periodically disabling said verifier circuit for further change after one of said verifier flip-flops is set.

Claim 30

A combination as in claim 16 wherein said information outputting means comprises at least one decade display, and at least one decoder-driver means responsive to the output of said latching memory means for selectively activating said decade display.

Claim 31

A combination as in claim 27 further comprising additional receiving and transmitting transducers for producing relative frequency signals indicative of motion along at least one additional sensing axis, and means connected to said transducers for computing and displaying the direction and magnitude of motion along said additional sensing axis.

Claim 32

A combination as in claim 16 further comprising means for audibly reproducing one of said square wave signals.

Claim 33

A combination aS in claim 2 further comprising means for computing the distance travelled by said system along said sensing axis.

Claim 34

A combination as in claim 30 wherein said distance computing means includes means for developing a digital square wave train having a frequency reflecting the difference in frequency between the emitted and returned signals, means for determining the relative direction of motion of said transducer means along said sensing axis, an up-down counter having up and down count input terminals, first and second gating means for connecting said square wave train to said up and down counter input terminals, respectively, said relative direction determining means including means for selectively enabling only one of said first and second gating means.

Claim 35

A combination as in claim 31 further comprising means for correcting said distance computing means for variations in the characteristics of the propagation medium.

Claim 36

A combination as in claim 32 wherein said correcting means comprises an oscillator, a flip-flop, a scaler connecting said oscillator to said flip-flop, variable frequency means having an output oscillation frequency dependent upon the propagation characteristic of said propagation medium, additional scaler means connecting said variable frequency means with said flip-flop, means connecting the output of said first scaler to initialize said second scaler, and further gating means for selectively isolating the up and down counter input terminals of said up and down counter responsive to signaling from said flip-flop.

Claim 37

A combination as in claim 2 further comprising means for computing the velocity of said vessel along two orthogonal sensing axes, and means responsive to said orthogonal velocity computations for computing the instantaneous drift angle of said system.